I have export the avatar to Unreal, everything works well before I try to export the project to IOS platform. But When I try to export it to the IOS platform, there are some warning like: "PackagingResults: Warning: [AssetLog] /Users/wujinyao/Desktop/MyProject3/Content/CC_Shaders/EyeOcclusionShader/RL_EyeOcclusion.uasset: Failed to compile Material for platform SF_METAL, Default Material will be used in game." And the avatar in my ipad only had the grey head, without any texture or color. I don't know how to fix it, can anyone help me? Thank you so much!